Abscisic-acid-dependent regulation of Arabidopsis thaliana ammonium transport relies on ABI1 control of CIPK23 and AMT1
Abscisic-acid-dependent regulation of Arabidopsis thaliana ammonium transport relies on ABI1 control of CIPK23 and AMT1
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DOI：
10.1101/2021.02.09.430435
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发表时间：
2021-02
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通讯作者：
P. Ganz;Romano Porras-Murillo;Toyosi Ijato;Jochen Menz;Tatsiana Straub;Nils Stührwohldt;Narges Moradtalab;U. Ludewig;B. Neuhäuser
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作者：
P. Ganz;Romano Porras-Murillo;Toyosi Ijato;Jochen Menz;Tatsiana Straub;Nils Stührwohldt;Narges Moradtalab;U. Ludewig;B. Neuhäuser
植物根系对氨的吸收在转录、转录后和翻译后水平上都受到调控。蛋白激酶CIPK23的磷酸化可暂时失活AMT1，但激活AMT1的磷酸酶尚不清楚。在这里，我们已经确定PP2C磷酸酶ABI1是拟南芥AMTS的激活剂。我们发现，高浓度的外源铵通过脱糖作用提高了植物激素脱落酸(ABA)的含量。通过ABI1-PYL复合体感受到ABA的活性，然后ABI1激活CIPK23失活。在有利的生长条件下，ABI1通过结合和失活CIPK23以及通过AMT1的直接去磷酸化来减少AMT1的磷酸化。因此，ABI1是氨吸收的正调节因子，将营养获取与非生物胁迫信号相结合。在胁迫情况下，ABA升高会减少对铵的吸收，例如氨中毒，而ABI1在有利的生长条件下会重新激活AMT1。
Ammonium uptake at plant roots is regulated at the transcriptional, post-transcriptional and post-translational levels. Phosphorylation by the protein kinase CIPK23 transiently inactivates the ammonium transporters (AMT1s) but the phosphatases activating AMT1s remain unknown. Here, we have identified the PP2C phosphatase ABI1 as an activator of AMTs in Arabidopsis thaliana. We show that high external ammonium concentrations elevate the stress phytohormone abscisic acid (ABA) by de-glycosylation. Active ABA is sensed by ABI1-PYL complexes followed by the inactivation of ABI1 activating CIPK23. Under favourable growth conditions, ABI1 reduces AMT1 phosphorylation, both by binding and inactivating CIPK23, and by the direct dephosphorylation of AMT1s. Thus, ABI1 is a positive regulator of ammonium uptake, coupling nutrient acquisition to abiotic stress signalling. Elevated ABA reduces ammonium uptake during stress situations, such as ammonium toxicity, whereas ABI1 reactivates AMT1s under favourable growth conditions.